Push-button operated switch, more particularly for doors and the like

ABSTRACT

This invention provides a door lock having a non-rotatable door knob of hollow construction housing a lock-operating mechanism so arranged that the associated latch can be retracted by depressing a spring-loaded push-button mounted on the knob and projecting laterally outside the circumference of the knob. A complementary operating arrangement may be provided for a knob mounted on the other side of the door.

United @tates Patent [191 Meroni Mar. 4, 1975 PUSH-BUTTON OPERATEDSWITCH,

MORE PARTICULARLY FOR DOORS AND THE LIKE [75] Inventor: GiuliandreaMeroni, Nova Milanese,

Italy [73] Assignee: Cicala Establishment, Vaduz,

Liechtenstein [22] Filed: Dec. 8, 1972 [21] Appl. No.: 313,387

[30] Foreign Application Priority Data Mar. 15, 1972 Italy 21872/72 July27, 1972 Italy 27529/72 [52] U.S. C1. 292/166, 70/462 [51] Int. Cl. E05c1/12 [58] Field 01 Search 292/166, DIG. 37, 221; 70/462, 336.3

[56] References Cited UNITED STATES PATENTS 224,040 2/1880 Prouty292/166 1,133,437 3/1915 Holt 292/166 1,150,186 8/1915 292/166 1,479,6021/1924 292/166 2,504,483 4/1950 292/166 2,547,546 4/1951 Stulpin et a1292/166 FOREIGN PATENTS OR APPLICATIONS 11,901 10/1885 Great Britain292/166 Primary Examiner-J0rd0n Franklin Assistant E.\'aminerPeterNerbun.

Attorney, Agent, or Firnz-Sughrue, Rothwell, Mion, Zinn & Macpeak [57]ABSTRACT This invention provides a door lock having a nonrotatable doorknob of hollow construction housing a lock-operating mechanism soarranged that the associated latch'can be retracted by depressing aspringloaded push-button mounted on the knob and projecting laterallyoutside the circumference of the knob. A complementary operatingarrangement may be provided for a knob mountedon the other side of thedoor.

6 Claims, 22 Drawing Figures PATENTED 4l975 sum 3 er 9 Figs PATENTED41975 3, 869a 1'61 SHEET 8 if 9 FIG. 13

PATENIEDHAR 41515 3.869.161

sum 9 5 9 FIG. 21

- lllllll I 1 PUSH-BUTTON OPERATED SWITCH, MORE PARTICULARLY FOR DOORSAND THE LIKE BACKGROUND OF THE INVENTION Various door locks are known,the commonest being the type in which a door knob is rotatably mountedon the door and in which partial rotation of the knob against resilientmeans brings about retraction of a latch. This known type of lock with arotatable knob, whilst being easy to use, is of complicatedconstruction, and is therefore expensive to manufacture. Moreover, doorlocks of this type necessitate a locking arrangement operable by meansof a key inserted in a keyhole located in a position separate from thedoor knob. I

Another known type of lock uses a rotatable knob which retracts a latchupon rotation of the knob in either direction, against a springreaction. This type of lock is also of complicated construction, due tothe considerable number of parts required for transmission of therotarymovement from the knob to the latch. Moreover, this type of lock alsosuffers from an installationaldisadvantage in that it has to be fittedat a height, above the ground such as to allow convenient operation bythe user.

A third known type of lock is the one in which a knob is mountednon-rotatably on a door and control of the retraction of a latch iseffected by means of a pushbutton extending axially within the knob.This type of lock also has various disadvantages, both of a structuralnature, which make the lock costly to produce, and from the viewpoint ofease of operation since the user has to operate the push-button ingeneral with the thumb. Also this type of push-button lock usuallyentails the provision of devices for'locking the latch, for example bymeans a key insertable in a keyhole separate from the knob, entailingboth constructional difficulties and difficulties offitting.

OBJECT OF THE INVENTION An object of the invention is to provide a lockwhich on the one hand avoids the disadvantages of the types of lockmentioned above andon the other hand combines the advantages of theseknown locks, as well as adding peculiar advantages of its own.

More particularly, an object of the present invention is to provide alock which is easy to use, of simple construction, and thereforeeconomical to manufacture, as well as being easy to fit to doors ofdifferent thicknesses and to padded doors.

A further object of the invention is to provide a lock in which thedevices controlling the latch, and the locking devices for the latterare conveniently re-arranged, allowing'a choice of control of the lockby means of a key or control of another nature on either one side orboth sides of the door or anyother type of control.

Another object of this invention is to provide a lock with push-buttoncontrol capable of being mounted both on doors which open to the rightand doors which open to the left, thus avoiding another disadvantage oflocks of known types.

Yet another object of this invention is to provide a lock of theabove-mentioned type having structural and functional characteristicswhich are substantially simplified and which is simple and economical toproduce.

A specific object of a preferred embodiment of the invention is toprovide a lock in which the position of the push-button is such that itis easily operable without requiring installation at a predeterminedheight above the ground and without compromising the otherconstructional and functional requirements of the lock mechanisms.

SUMMARY OF THE INVENTION According to the present invention there isprovided a lock with a push-button control for doors and the like,comprising at least one knob for the movement of the door, a latch, anda control push-button controlling the latch of the lock, wherein theimprovement consists in the knob having means of non-rotatableattachment to the door, and means defining an interior cavity asupporting device within the knob cavity, and latch control meansmounted on said supporting device, said control means being associatedwith said push-button, and said push-button being operable from outsidethe circumference of the knob.

In a preferred embodiment of the invention the lock includes two knobshavingmeans of non-rotatable attachment to opposite sides of the door,and respective said supporting devices for the latch control means,housed in the cavity of each knob and independently thereof, saidsupporting devices being provided with respective. anchorage meansadapted to pass through the thickness of the door and interengageablewith each other, means operable from outside the lock for locking andunlocking the latch control means, said means for locking and unlockingbeing located in the cavity of the respective knob.

Preferably the means operable from outside circumference ofthe knobis'movable with respect to the knob in a direction substantiallyparallel to the plane of the door.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described,by way of nonlimiting example, with reference to the accompanyingdrawings, in which: a

FIG. 1 is a diagrammatic perspective view illustrating a lock accordingto this invention mounted on a door, part only of which is shown;

FIG. 2 is an axial section on an enlarged scale, taken on line II II- ofFIG. 1;

FIG. 3 is an enlarged axial section of part of the lock, similar to FIG.2, showing the lock in the open position;

FIG. 4 is a transverse cross-section on line IV IV of FIG. 2;

FIG. Sis a partial axial section taken on line V V of FIG. 2;

FIG. 6 is an exploded perspective view of the lock;

FIG. 7 is an exploded perspective view, on an enlarged scale of theelements contained in the hollow interior of one of the door knobs tothe lock;

FIG. 8 is a further exploded perspective view of the elements containedin the interior of one of the door knobs with particular reference tothe locking means for the latch;

FIGS. 9 and 10 are diagrammatic axial sections, similar to FIG. 5, ofvariations of the type and positioning of the control push-button of thelock;

FIG. 11 is a partial axial section of a lock according to a firstvariant of the invention applied to a door;

FIGS. 12 and 13 are plan views from above and in partial axial sectionof the lock of FIG. 11 in the position in which the latch is extendedand the latch retracted respectively;

FIG. 14 is an exploded perspective view of the mechanism for operatingthe latch of the lock of FIG. 11;

FIGS. 15, 16, -l7.represent constructional details of the lock of FIG.11;

FIG. I8-depicts in perspective and in separate parts the mechanism foractuating the latch in one embodiment of the lock according to thisinvention, a lock intended particularly use on interior doors;

FIGS. 19 and 20 are lateral elevational views of the mechanism of FIG.18 in two positions of operation, and

FIGS. 21 and 22 show the latch operating mechanism of FIG. 18 viewedfrom above in said two positions of operation DETAILED DESCRIPTION OFTHE ILLUSTRATED EMBODIMENTS With reference to the drawings, referencenumeral 1 indicates part of a door on which a lock according to thisinvention is mounted. The lock has two operating handles in the form ofhollow knobs 2,2 symmetrically arranged non-rotatably on the oppositesides of the door and aligned on an axis perpendicular to the plane dothe door.

In the following description of the knob 2 it will be understood theother knob 2' has a corresponding internal mechanism.

The knob 2 has a base wall 3 adapted to be placed in contact with oneface of the door 1. The knob 2 has an external end wall 4 which may beof plastics material provided on its outer periphery with teeth 5 forreleas- 0 which the pivot pin 21 passes and a longer arm 25 at rightangles to the arm 23. The arm 25 extends through the thickness of thedoor 1, terminating in a rounded end portion 25a situated in a planedifferent from the plane of the remainder of the arm 25. From the shortarm 23 an appendage 26 projects perpendicularly, having on one face astud 27 of material such as plastics with a low friction coefficient.The studs 27 face towards the short arm 17b of the primary lever 17. Theend portion 25a of the long arm 25 passes through a slot 29 in the baseplate 9 of the support 8 and into a space out out of the door, so as tooperate a movable latch as will be described hereinafter. The upper arm17a of the primary lever 17 cooperates with a control push-buttonmovably mounted in an aperture 32 in the wall of the knob 2. The button30 is provided with projections 31 which engage behind the upper wall ofthe knob 2 and prevent dis-engagement of the button 30 from the knob, Inthe example illustrated in each knob 2, 2 the respective controlpush-buttons 30, 30' are both arranged in the top walls of the knobs: itwill, however, be self-evident that the push-button could alternativelybe arranged in any other radially projecting positions around thelongitudinal axes of the respective knobs. I

The cranked secondary lever 22 is acted upon by a spiral spring 28 whichurges the lever 22 into a repose position, shown in FIG. 2, in which therear appendage able snap engagement in the cavity of the knob. A tuholeextending parallel to the longitudinal axis of the knob 2.

Inside the knob 2 there is arranged a supporting device 8' (FIG. 7)constituted by a transverse base .plate 9, arranged against the basewall 3 parallel to the door face and by a lower support plate 13integral with the base plate 9. In one of the knobs, 2, the base plate 9is provided with a pair of orifices 10 for the passage of two fixingscrews 11 intended to be screwed into internally-threaded tubes 12 fixedto. the supporting device of the other knob 2', thereby clamping the twosupporting devices to the opposite faces of the door 1. By adjusting thescrews 11 in threaded tubes 12 it is possible to adapt the lock easilyto doors of different thicknesses without any modification to thecomponent parts.

Two upstanding parallel stirrups 16 are formed integrally on oppositesides of the lower support plate 13, the stirrups 16 having holes attheir ends in which a pivot pin 19 carrying a cranked primary lever 17(FIGS.1 to 8) is supported, the lever 17 having lateral apertured lugs18 in which the pivot pin 19 engages. The primary lever 17 has an uppercurved arm 17a and a shorter lower arm 17b which faces towards the baseplate 9.

Two inwardly projecting parallel lugs 20 are cut out from the base plate9. A secondary actuating lever 22 is freely rotatable about a verticalpivot pin 21 carried by the lugs 20. The secondary lever 22 iscrank-shaped and has a short arm 23 provided with a hole 24 through 26of the lever 22 rocks the primary lever-l7 in such manner as to push thepush-button 30 radially outwardly from the knob 2. By depressing thepush-button 30 by hand the primary lever 17 is rocked in a clockwisedirection, as viewed in FIG. 5, causing corresponding rotation of thecranked secondary lever 22 about the vertical pivot pin 21 so as to movethe end portion 250 and retract the latch.

The displaced end portion 25a of the lever arm 25 so formed as to allowthe end portion 25a to lie side-byside, without interference, with thecorresponding end portion 25'a of the secondary lever of the mechanismassociated with the other knob 2', the two end portions being displacedsymmetrically in opposite directions, enabling adaptation of the lock todoors of different thicknesses or padded doors.

Each latch control means is provided with a lock to prevent opening ofthe doors to each support device 8 there is fixed a block 15 for exampleof plastics material, fixed by means of screws 14 or other equivalentmeans, to the lower support plate 13: the block 15 has a transversechannel 33 in which a plate 34 having an elongated through slot 35 ismounted rotatably. A locking rod 36 of rectangular cross section whichpasses through holes 38 in the base plate 9 of each of the two supportdevices 8 and through holes in the base walls 3, 3' of the two knobs 2,2'. Therod 36 passed through a respective bore 37 in each block 15, andis coupled to each respective plate 34 located within each of the twoknobs by engagement in the respective slots 35 of the plates 34.Alternatively, a plate may be provided in only one of the knobs forengagement by the rod 36. In the example depicted in FIG. 5 there isprovided a small hollow cylinder 39 which is rotatably mounted in thebush 6 integral with the outer end wall 4 of the knob 2. One end of thelocking rod 36'is inserted into the hollow cylinder 39. One end of thecylinder 39 projects outwardly of the knob 2 and carries an externalappendage 40 in the form for example of a small knob operable manuallyto rotate the rod 36 about its longitudinal axis and thereby also rotatethe two plates 34 into the path of oscillation of the appendage 26 ofthe two crank levers 22, preventing operation of the push-button 30. v

The other knob 2 may be provided with a barrel lock 41 having a key 41a(FIG. 6) by means of which the same angular displacement of the lockingrod 36 may be effected from the outside of the door.

With particular reference to FIG. 8 the lock 41 has a barrel 142 fixed,by screws or equivalent means, to the bottom support plate 13 of thesupport 8. The barrel 142 is provided with two lateral recesses whichdefine lateral shoulders 144. The shoulders 144 are engageable withrespective dogs 145 projecting laterally inwardly from fins 146 providedon the internal face of the respective front wall 4'. Once the frontwall 4 has been fitted in position the engagement of the dogs 145 withwith the shoulders 144 prevents easy removal of the front wall 4,thereby guaranteeing security of the lock 41. Manual control of the rod36 may be effected by any other means already known, such means beingassociated withone or both of the knobs 2 and 2.

When the locking means, constituted by the rod 36, thetwo plates 34 andthecontrol devices connected thereto, is caused to pass from theunlocked or repose position to the locking position, shown in FIG. 5,each plate 34 is located, as stated above, behind the appendage 26 ofthe cranked lever 22, preventing angular movement of the lever 22 bymeans of the lever 17 and the push-button 30. When on the other hand thetwo plates 34 are returned to the repose position, they are retractedinto the channels 33'of the respective blocks 15, allowing actuation ofthe two levers l7 and 22.

With particular reference to FIG. 6, a latch 42 is mounted for movementaxiallyin a casing 43 which can be inserted into a blind hole made inthe free edge of the door parallel to its principal faces. The casing43has at one end a face-plate 44 which lies flush with the edge of thedoor and at the other end has seats 45 through which pass the threadedtubes 12 which contain the anchoringscrews 11, the said tubes extendingtransversely with respect to the longitudinal axis of the casing. 43. Inthe case in whichthe screws 11 and the tubes 12 are replaced byotherequivalent fixing devices, the seats 45 can be dispensed with.

The latch 42 carries at its inner or rear end a moulded slide 46consisting for example of plastics material having a low coefficient offriction with respect to the casing 43. The slide 46 has a lateralthrough slot 47 in which engage, on opposite sides, the end portions 25aand 25 'aof the respective cranked secondary levers 22. The end portions25a and 25 'a are partially superimposed in the saidslot 47, to anextent dependent I the spiral spring 28, acting on the lever 22, and anin ternal spring 49 acting on the latch 42, cause the movable parts toreturn to the normal position of closure 0 the lock (FIG. 2). Assemblyof the lock on the door is particularly simple, necessitating only theprovision of (a) a transverse which interconnect the two knobs, and forhousing the end portions 25a, 25a of the levers 22, 22 and (b) a morticein the free edge of the door parallel to the faces of the door forhousing the casing 43 of the latch 42. The lock may have many variationsas regards the form and dimensions of the knobs 2 and 2', since thesupport devices 8 and the means mounted thereon may be housed in knobsof any desired form. The end walls 4 and 4 are also made, for example,of plastics material and make it possible to obtain particular chromaticeffects incombination with the push-buttons and 30, which may also be ofplastics material. The lock also lends itself to eccentric mounting onpadded doors.

The positioning of the projecting ends of the pushbuttons operable fromoutside the circumference of the knobs, and the direction of movement ofthe, pushbuttons, may also be varied, while the other characteristics ofthe lock remain unchanged.

For example referring to FIG. 9 a variant of the lock is shown in whichthe push-button 50 is movable along the longitudinal axis of the knob 2,that is, perpendicular to the plane of the door 1 and acted upon aspring 51 reacting against a shoulder 52 fixed to or integral with thesupporting device 8. The inner end 53 of the push-button 50 bearsdirectly'against the appendage 26 of the cranked secondary lever 22,to'effect operation of the lock as described previously. The plate 34 isshown in FIG. 9 in its locking position.

Analternative variant, shown in FIG. 10, has a pushbutton 54 housed in-ahollow knob 55 of different form from the knobs 2 and 2': thepush-button 54 acts in a direction which is inclined with respect to theplane of the door 1. The push'button 54 is operatively associated with'alever 56 pivoted at57 "to a pair of ears 58 provided on the supportingdevice 8. The lever 56 acts upon an appendage 26 of the secondary lever22 with the interposition of an anti-friction contact stud 27. Thesecondary lever 22 has another-appendage 26 in whichthis examplecooperates with the movable plate 34 of the locking mechanism.

' The knob 55 has an outer port 59 which in the illustrated embodimentis inclinedto the axis of the knob V and is provided with a lower recess60 for engagement by a finger when the knob is gripped.

FIGS. 11 17 show a first variant of a lock according to this invention.The lock can be fitted equally well to doors which open to the right orto the left. In the description which follows the same reference numbersare used for those parts of the lock of this variant which correspond toparts of lock shown in FIGS. 1 to 8.

In this first variant each of the hollow knobs 2 and 2" houses asupporting device 8 which is constituted by a hole in the door forhousing the tubes 12 and screws 11 transverse base-plate adapted to bemounted in close contactwiththe base wall 3 of the respective knob, andby a support element 106 shaped essentially like a stirrup of transverseU-section and upstanding from the base-plate 105. The lateral walls 107and 108 of the stirrup like support element. 106 are near their upperedges traversed by through holes 109, 110 respectively. A pivot pin 19providing a pivotal support of the first cranked lever 17 engages in theholes 109, 110. The base-plate 105 is provided centrally with arectangular aperture 113 and two brackets 114, 115 are formed in thebase-plate 105 on opposite sides of the aperture 113, the brackets 114,115, being formed, for example, by partial cutting and successivefolding of the cutout portions along their non-cut sides.

Between the brackets 114 and 1 there are pivoted and freely rotatabletwo actuating levers 117, 118 both of which are articulated to avertical pivot pin 49 associated with the said brackets 114, 115. Eachof the levers I17, 118 is essentially of cranked form and has a longerarm 120 120a extending through the aperture 113 of thebase-plate 105 andinto an aperture in the door 1. Each lever 117, 118 also has a shorterarm 121, 121a which is perpendicular to the longer arm 120, 120a andprojects towards the base of the stirrupshaped support element 106, eachshorter arm I21, 121a being in practice parallel to the base plate 105.On the face of each shorter arm 121, 1210 facing away from the baseplate 105 there are provided studs 27, 27a of synthetic plasticsmaterial with a low coefficient of friction.

The levers 117, 118 are superimposed like a pair of scissors, the commonpivot axis of which coincides with the pivot pin 119 on which bothlevers are mounted. The levers 117, 118 are biased towards a closedposition of substantial coincidence by a spring 123 associated with thepivot pin 119 the ends of the spring engaging in small notches 124, 125provided respectively on the external edges of the said levers 117, 118.The top arm 17a of the lever 17 cooperates with the pushbutton 30.

Under repose conditions, the action of the spring 123 prevails so thatthe levers 117, 118 are closed, that is, the levers 117, 118 aresuperimposed and parallel to each other whilst the short arms 121, 121aof the levers are reciprocally in close contact and aligned parallel tothe base-plate 105. I

Under these conditions, the studs 27, 27a of the crankedlevers 117, 118which are spaced from the axis of the pivot pin 119, FIG. 14, displacethe lever 17 into the position shown in FIG. 11 and the lever 17 in turndisplaces the push-button 30 upwards so that it projects out of the knob2. Again, in the repose position, the longer arms 120, 1200 of thelevers 117, 118 which extend through the aperture 113 in the plate 105,are engaged in a slot47 formed in a slide 46 associated at the rearwiththe lateh42 and movable therewith.

By depressing the push-button 30 the lever 17 is rotated anti-clockwiseas viewed in FIG. 11 so that its short arm 17b presses on the studs 27and 27a of the levers 117, 118. By virtue of this pressing action andthe displacement of the studs 27, 27a with respect to the axis of thepivot pin 119 of the levers I17, 118 the two levers I17, 118 tend to bespread apart so that their longer arms 120, 1200 open in scissorsfashion.

With reference to FIGS. 11 and 12, and assuming that pressure isexertedon the push-button 30 of the knob 2 (relatively to which the door 1-opens to the right), the abovementioned spreading-out of the levers 117,118 causes retraction of the slide 46, with conse quent retraction ofthe latch 42. This retraction results from the action of the longer arm120 of the top lever 117 on the rear wall 290 of the slot 47 in the saidslide 46. Upon cessation of the pressing action on the pushbutton 30 thespring 48 returns the latch 42 to its extended position of closure.

If pressure is exerted on .the push-button 30' of the knob 2'(relatively to which the door 1 opens to the left) the abovementionedscissors-like spreading-out of the longer arms 120,120a of the pairoflevers 117, 118 again brings about retraction of the slide 46 andconsequently of the latch 42; in this case the retraction is due to thelonger arm a of the lower lever 118 of the pair of levers 117, 118.

The lock may therefore be applied equally well to doors opening to theright and doors opening to the left, without making modifications in thepositioning of the component parts or varying the configuration of theseparts. The lock of FIGS. 11 17 may also be provided with lockingarrangements as described for the lock of FIGS. 1 to 8.

FIGS. 15, 16 and 17 illustrate in detail some structural details of thelock according to this first variant of the invention. Moreparticularly, in FIGS 15 and 16 the levers 117 and 118 are shownseparately in plan. It will be seen that the levers 117, 118 have flatportions 134, 135 respectively, the edges of which include shoulders136, 137 which abut under repose conditions against the base-plate 105FIGS. 14 and 17. The outer edges of the flat portions 134, 135 alsoinclude respective reentrant notches 124,- adjoining the lines of foldof the respective shorter arms 121, 121a of the cranked levers 117, 118,in which notches 124, 125 the opposite ends of the spring 123 engage.FIG. 17 shows a frontal and external view of the stirrup element 106 andthe plate 105. In this Figure the shape of the aperture 113, isdesignated by a thickened line. The edges of the aperture 113, adjacentthe sides from which the brackets 114, 115 project are formed withrespective slots I38, 139, which are arranged symmetrically on oppositesides of a diameter of the base-plate 105 and are dimensioned so as toallow rotation of the levers 117, 118. In fact the presence of the slots138, 139 allows respective tongues 134a and 135a on the flat portions134, 135 ofthe said levers 117, 118 to pass through the plate aperture113.

In FIGS. 18 to 22 show a second variant of a lock according to theinvention, which being simplified, may with advantage be applied tointerior doors.

According to this variant a circular base-plate 209 bears against thebase wall 3 of each knob. The baseplate 209 is formed with a singlecentrally disposed brackets 220, projecting perpendicularly to thebaseplate 209 into theinternal cavity of the knob (not shown). Thebracket 220 pivotally supports in a freely rotatable manner a crankedlever 222 having a longer arm or finger 225 which passed through anaperture 229 provided centrally in the base-plate 209.

The shorter arm 223 of the lever 222 is pivotally connected to thebracket 220 by a screw 224 which passes through a hole 2240 in the arm223 and engages by a screwing action in a threaded hole 220a in thebracket 220. The longer arm or finger 225 of the cranked lever 222, isadapted to engage in the manner previously described, with the latch ofthe lock.

The cranked lever 222 is provided in a central position on its shorterarm 223 with an integrally formed tongue 226, bent at right angles tothe arm 223 and in practice parallel to the base-plate 209, from whichit is spaced by a distance practically equal to the height of thebracket 220 above the base-plate 209. On the face of the tongue 226turned towards the interior of the knob there is provided a stud 226a orraised portion advantageously made of synthetic plastics material havinga low coefficient of friction with respect to those parts with a toppart 217a which cooperates with a pushbutton (not shown) mounted inthe-knob, as previously described. The other part 217b of the lever 217projects downwardsand terminates in two folded lips 319 which facetowards the base-plate 209. This part 217b of the lever 217 isconstantly in contact with the stud 226a of the lever 222.

The lever 217 is provided in an intermediate position between the twoparts 217a and 217b, with a pair of parallel spaced apart arms 318, 319which are formed with hooked ends 318a, 319a respectively, moulded withrespective notches 320, 321 which face towards the push-button, that is,upwards in the position of use. The notches 320, 321 are practicallyequal in width to the thickness ofthe base-plate 209 and advantageouslyare delimited by flanks which diverge from the bottom of each notch. Thehooked ends 318a and 3190 are adapted to engage releasably in respectiverectangular through slots 322, 323' provided in the top portion of theplate 209. Each engagement, by virtue of the dimensions of the notches320 and 321 and the diver gence of the flanks of the latter, is apivotal engagement so that the notches 320 and 321 define the fulcrum ofthe lever 217.

By pressing on the push-button, not shown, the top part 217a of thelever 217 is depressed, and the lever 217 is rocked around the fulcrumdefined by the notches 320 and 321 so that the part 2171; of the thelever presses against the stud 226a of the lever 222, causing the latterto rotate about its pivot pin 224, and

is interposed between the base-plate 209 and one of the lips 317 of thelever 217, thus preventing rocking movement of the latter around itsfulcrum point and preventing actuation of the finger lever 222.

I claim:

1. A door latch mechanism of the type having a pushbutton controlcomprising a latch movably mounted in a door, at least one hollow knobhaving a central axis, means for non-rotatably securing said knob to adoor with said central axis disposed perpendicular to the door,supporting means secured within said knob, latch control means pivotallymounted on said supporting means and operatively engaged with saidlatch, aperture means in said knob, a push-button movably mounted insaid aperture for movement substantially transverse to said central axisand disposed in operative engagement with said latch control means, saidlatch control means being comprised of a pair of substantiallyscissors-like levers mounted on a common pivot carried by saidsupporting means, one end of each of said levers being operativelyassociated with said pushbutton and the other end of each of said leversbeing operatively engaged with said latch and resilient means engagingsaid levers to oppose spreading out of the levers.

2. A door latch mechanism as set forth in claim 1, further comprising anadditional lever pivotally mounted on said supporting means intermediatesaid push-button and said one end of each of said levers to therebymoving the larger arm or finger 225 to retract the latch of the lock.

The lock of FIGS. 18 20 is provided with a locking arrangement indicatedgenerally by 240, to lock releasably the actuating mechanism for thefinger lever 222. This locking arrangement is constituted by a platelike element 240 rotatably mounted on the plate 209 in a positiondiametrically opposedv to the portion in which the slot 322, 323 areformed. This plate like element 240 is centrally traversed by arectangular orifice 242 aligned with a hole 238 in the base-plate 209.The plate like element 240 is provided with an upper arcuate slot 243the centerline of which is an arc of a circle having as centre thecentre of the orifice 242. Rotation of the plate like element 240 aboutthe centre of the orifice 242 is guided by the engagement of a stem 245in the arcuate slot 243, the stem 245 being attached to or integral withthe plate 209. Advantageously the stem 245 is constituted by a screwwhich is screwed into a threaded orifice 245a in the base-plate 209. Theplate like element 240 has a lower appendage 246 bent through 90 andprojecting into the interior of the knob a distance equal to thedistance between the plate 209 and the lips 317 of the lever 217 whenthe latter is in the repose position.

In the rectangular of orifice 242 of the element 240 a locking rod 236of conjugate cross section engages. The locking rod 236 is rotatableabout its longitudinal axis to cause rotation of the plate like element240 so as to move the appendage 246 from its lowermost position shown inFIG. 18 to a locking position in which it spread apart the ends of saidscissors-like levers upon depression of said push-button.

3. A door latch mechanism as set forth in claim 1, further comprising asecond substantially identical door knob non-rotatably connected to saidfirst mentioned knob and adapted to be disposed on the opposite side ofthe door with the central axis thereof aligned with the central axis ofthe first mentioned knob, said second'knob having a push-button,supporting means and latch control means constructed and arrangedsimilar to the corresponding means in said first mentioned knob foroperating said latch and locking means for selectively locking andunlocking said latch control means.

4. A door latch mechanism as set forth in claim 3, wherein said lockingmeans is comprised of a rod rotatably mounted in at least one of saidknobs for rotation about an axis parallel to said central axis of saidknob, a locking element connected to said rod and adapted to be rotatedby said rod between a first locking posi tion to prevent pivotalmovement of said latch control means and a second unlocking position,and means externally of said knob for rotating said rod.

5. A door latch mechanism as set forth in claim 1,

, wherein said latch control means is comprised of a furto the plane ofthe door.

1. A door latch mechanism of the type having a push-button controlcomprising a latch movably mounted in a door, at least one hollow knobhaving a central axis, means for non-rotatably securing said knob to adoor with said central axis disposed perpendicular to the door,supporting means secured within said knob, latch control means pivotallymounted on said supporting means and operatively engaged with saidlatch, aperture means in said knob, a push-button movably mounted insaid aperture for movement substantially transverse to said central axisand disposed in operative engagement with said latch control means, saidlatch control means being comprised of a pair of substantiallyscissors-like levers mounted on a common pivot carried by saidsupporting means, one end of each of said levers being operativelyassociated with said push-button and the other end of each of saidlevers being operatively engaged with said latch and resilient meansengaging said levers to oppose spreading out of the levers.
 2. A doorlatch mechanism as set forth in claim 1, further comprising anadditional lever pivotally mounted on said supporting means intermediatesaid push-button and said one end of each of said levers to spread apartthe ends of said scissors-like levers upon depression of saidpush-button.
 3. A door latch mechanism as set forth in claim 1, furthercomprising a second substantially identical door knob non-rotatablyconnected to said first mentioned knob and adapted to be disposed on theopposite side of the door with the central axis thereof aligned with thecentral axis of the first mentioned knob, said second knob having apush-button, supporting means and latch control means constructed andarranged similar to the corresponding means in said first mentioned knobfor operating said latch and locking means for selectively locking andunlocking said latch control means.
 4. A door latch mechanism as setforth in claim 3, wherein said locking means is comprised of a rodrotatably mounted in at least one of said knobs for rotation about anaxis parallel to said central axis of said knob, a locking elementconnected to said rod and adapted to be rotated by said rod between afirst locking position to prevent pivotal movement of said latch controlmeans and a second unlocking position, and means externally of said knobfor rotating said rod.
 5. A door latch mechanism as set forth in claim1, wherein said latch control means is comprised of a further leverpivotally mounted on said support device and interposed between the endof the push-button within the knob and said scissors-like levers.
 6. Adoor latch mechanism as set forth in claim 1, wherein said push-buttonis movable in a plane parallel to the plane of the door.